Transflective liquid crystal display

ABSTRACT

The apparatus, methods, system and devices of the present invention provides transflective LCD system structure wherein each pixel is composed of at least three reflective sub-pixels and at least one transmissive sub-pixel. The reflective sub-pixels have a color filter layer for displaying color reflective images and the transmissive sub-pixel it is driven by color sequential imaging method for displaying a color transmissive image. The configuration of the sub-pixels and the location of the sub-pixel electronics increases the aperture ratio of both transmissive sub-pixel and reflective sub-pixel to improve the image brightness and lower the overall power consumption of the device.

FIELD OF THE INVENTION

This invention relates to transflective liquid crystal displays and, inparticular, to apparatus, methods, system and devices for atransflective liquid crystal display having a pixel structure includingat least three reflective sub-pixels and one transmissive sub-pixelwhich improves the aperture sizes of both reflective and transmissivesub-pixels to provide brighter image for both reflective andtransmissive modes.

BACKGROUND AND PRIOR ART

Since liquid crystal display (LCD) was discovered, two types of the LCDhave been developed and widely used in information display tools,including cell phones, laptops and desktop computers, televisions, andso on. One type is the transmissive LCD which employs a light sourcecalled “backlight” at the back side of the liquid crystal cell. Theother type is the reflective LCD which uses ambient light as a lightsource instead of backlight to display an image. Because of usingambient light, the reflective LCD consumes less power than thetransmissive LCD so that it is more suitable for portable electronicdevices which require low power consumption. However, under the darkambient, the reflective LCD cannot show the image well. The transmissiveLCD, on the other hand, shows the high quality image under the darkambient because it has its own built-in light source.

To take the advantages and overcome the disadvantages of bothtransmissive LCD and reflective LCD, the transflective LCD is proposed.Transflective LCD means it can display an image in transmissive displaymode and reflective display mode independently or simultaneously.Therefore, such a transflective LCD is designed to be used under anyambient circumstances.

To realize the transflective LCD, some amount of incident light fromambient should be reflected back to the reviewer, and at the same time,some amount of backlight should transmit the LCD device and reach thereviewer's eye independently or simultaneously. The componentcontrolling the reflection and transmission of light is called atransflector hereafter. There are several approaches to realize thefunction of transflector.

One of the well-known technologies uses a partially transmitting mirrormade of very thin metal film. U.S. Pat. No. 4,093,356 issued to Bigelowon Jun. 6, 1978 disclosed a transflective LCD design using partiallytransmitting mirror. It provides the easiness of designing the devicestructure. However, to control the uniformity of the metallic filmthickness over a large area is not easy. This is especially true for theglass substrate used in the large screen-size LCD manufacturing. Insteadof the partially transmitting mirror, the semitransparent reflectorwhich has both fully transmitting part and fully reflecting part hasbecome popular in these days.

U.S. Pat. No. 4,040,727 issued to Ketchpel on Aug. 9, 1977 discloses atransflector based on discontinuous reflective film. An advantage ofthis kind of transflector is that it can easily control the area ratioof the transmissive part and the reflective part so that it provides theeasiness of optimizing the device performance for indoor-oriented oroutdoor-oriented applications. FIG. 1 shows a pixel structure 100 of thetoday's popular conventional transflective LCD which uses discontinuousreflective mirror. It consists of three primary color sub-pixels: Red101, Green 102, and Blue 103. Each color sub-pixel has a color filterlayer and a reflective mirror. Moreover, each sub-pixel furthercomprises a transmission region, which is denoted as 111, 112, and 113for each sub-pixel, respectively. Light from the backlight source cantransmit through this transmission region and it is responsible fordisplaying an image in the transmissive mode.

The transflective LCD based on discontinuous reflective film also hassome problems, including different electro-optic properties and unequalcolor reproduction between transmissive and reflective modes. To solvethe different color reproduction problem, Fujimori et al. proposed amethod using different thickness of color filters for transmissive andreflective parts as disclosed in Digest of Technical Papers of Societyfor Information Display 2002 International Symposium, p. 1382. Thismethod is effective to make the equal color reproduction fortransmissive and reflective images. However, it increases the complexityof the device fabrication process. As for the different electro-opticproperties of the transflective LCDs, there are several approaches toovercome this problem.

U.S. Pat. No. 6,281,952 issued to Okamoto et al on Aug. 28, 2001,discloses a transflective LCD which has different thicknesses of theliquid crystal layer on transmissive and reflective parts. In thereflective part, light passes through the liquid crystal layer twicewhile light in the transmissive part passes through the liquid crystallayer only once. By adjusting the thicknesses of the liquid crystallayer on transmissive and reflective parts, the same optical phaseretardation can be obtained in transmissive and reflective parts forboth ambient light and backlight. As a result, the equal electro-opticresponse for transmissive and reflective images can be obtained.However, to fabricate different cell gaps for transmissive andreflective parts, which is also called double cell-gap approach, is noteasy.

The '952 patent also discloses using different liquid crystal alignmentstructures for transmissive and reflective modes. In this configuration,the cell gaps for both transmissive and reflective parts can beidentical to each other. Even though this approach reduces thefabrication difficulty of the double cell gap structure; however, thedevice fabrication process is still not easy due to the complicatedalignment process. Another approach without increasing the fabricationdifficulty is using double switch devices, such as thin film transistors(TFTs), to control the reflective and the transmissive partsindividually and independently, as disclosed by Liu et al. in Proceedingof International Display Manufacturing Conference 2003, p. 215. Thistechnique is called a double TFTs driving method. However, this approachincreases the manufacturing cost because it requires twice as many datadriver ICs.

For direct view type LCDs, including the transflective LCD, oneimportant technical issue is how to improve the light efficiency so asto enhance the brightness of the image. One of the approaches is to usefour sub-pixels, including a white sub pixel, which was proposed by Leeet al in Digest of Technical Papers of Society for Information Display2003 International Symposium, p. 1212. Such a device design can lowerthe power consumption by about 50% to achieve the same brightness levelas the traditional LCDs. Another approach is to use the color sequentialtechnology to display the color image. U.S. Pat. No. 4,090,219 issued toErnstoff et al. on May 16, 1978 describes color sequential LCDtechnology. The basic concept of the color sequential technology is thatit displays the color image by sequentially drawn primary color imagesinstead of by the images of primary color sub-pixels. Therefore, thecolor sequential technology based transmissive LCD can use a colorswitching backlight and a single pixel without a color filter layer todisplay a full color image. It avoids the light absorption by the colorfilter and in the same time increases the pixel aperture size threetimes for each primary color compared to the conventional transmissiveLCD. As a result, the color sequential LCD increases the brightness ofimages and enhance the power utilization efficiency. Another advantageof color sequential LCDs is improved color reproduction capacity whenthe light-emitting diode (LED) backlight is used.

However, to realize the color sequential imaging, timing control of theLCD and the driving of backlight is very important. To understand thedriving scheme of the color sequential LCD, we need to understand thebasic principle of imaging method of the LCD called a line-at-a-timescanning method.

As shown in FIGS. 2 a and 2 b, a sub-pixel in the conventional LCDconsists of a pixel electronic circuit 210 and a pair of electrode andliquid crystal layer 220. The pixel electronic circuit consists of a TFT211 and a capacitor 212. One terminal of the TFT, called source or dataline 201, is connected to the data driver 240 of the system to get imagedata. One terminal of the TFT, called gate 202, is connected to the gatedriver or scan driver 250. The gate signal switches the TFT between theON and OFF states. When the TFT is ON, the data signal from the datadriver transfers to the drain terminal of the TFT which is connected tothe capacitor 212. The transferred data signal charges the capacitor 212and the voltage of the capacitor drives the liquid crystal layer 220.

As shown in FIG. 2 b, pixels in the same column are connected to thesame data line and all pixels in the same row are connected to the samegate line. The horizontal and vertical sync signals 230 synchronize thesignal process between the data driver 240 and gate driver 250. The scandriver 250 selects one gate line each time from the first row to thelast row. After the last row is selected, it restarts from the first rowagain. When one row is selected, the synchronized video signals from thedata driver 240 charge the capacitors of all of the pixels on theselected row. As a result, an image is drawn from top to bottom, row byrow. Using the capacitor 212, image data are stored during one period ofscanning, which is called one frame time. During one frame time, theimage is held until it is refreshed in the next frame time. The priorart imaging method described is referred to as a line-at-a-time scanningmethod.

The line-at-a-time scanning is shown in the timing diagram in FIG. 3.The y-axis represents the row number of the pixels in the LCD whilex-axis represents time. Thick slanted lines represent four successivetiming lines 311, 312, 313, and 314 for gate line scanning. The timeinterval between the timing lines of the gate line scanning signal forthe same row is the frame period. During the m^(th) frame period, theimage data 320 are held. FIG. 3 shows the image data 320 for the first,i^(th), and N^(th) rows, respectively. In the m+1^(th) frame period,image data 320 is refreshed by a next image data.

By applying the line-at-a-time driving method to the color sequentialLCD, the backlight device exposes red, green, and blue color light withline by line scanning. Each color light remains on during one sub-frameperiod or slightly shorter. In the next sub-frame period, anotherdifferent color backlight is turned on and hold for one sub-frameperiod. Consequently, after three successive sub-frame periods, the red,green, and blue backlight are each turned on once, with one sub-frameperiod, as shown in FIG. 4. FIG. 4 shows the red area 410, green area402, and blue area 403 showing the light exposing time for the rows ofpixels, respectively. Timing lines of row scanning 411, 412, and 413 arefor red 401, green 402, and blue 403 sub-frames, respectively. This kindof backlight device can be used in some specific single panel imagerbased projection displays, such as digital light processing (DLP) andliquid crystal on silicon (LCoS) systems. However, in the direct-viewtype LCDs it is very difficult to realize the abovementioned backlightdevice.

To solve this difficulty, several modified driving schemes weresuggested. One of them is using a blinking backlight as shown in FIG. 5.In the figure, red 401, green 402, and blue 403 light are turned on onlyin a short period, which is much shorter than the sub-frame period. Thescanning time of the gate line for a frame image 520 is shorter than onesub-frame period. When the last gate line is selected, the backlight isturned on until the first row is selected again in the next sub-frameperiod. Therefore, there exists an interval between the first gate lineis selected and the last gate line is selected, in which the backlightis turned off. However, the drawback of this method is it requires fastresponse liquid crystal mode and high intensity backlight source.

Another method is to use the dark sub-frame between two neighboringcolor sub-frames as shown in FIG. 6. Due to the use of the darksub-frame, the total number of sub-frames per frame period increasestwice compared to the previously described color sequential imagingmethods shown in FIG. 4. As shown in FIG. 6, the red 401, green 402, andblue 403 backlights are turned on during two successive sub-frameperiods. However, during these two successive sub-frame periods, thereis one image sub-frame and one dark sub-frame. Using the red backlight401 as an example, when the scan driver selects from the first row tothe last row, an image sub-frame is inserted following the timing line613 of row scanning 411. When the scan driver selects the first rowagain, which is the beginning of the next sub-frame period, a darksub-frame is inserted following the timing line of the next scanning611. Using the dark sub-frame, the time intervals of light exposure onall pixels is the same. An advantage of this method is that it is easyto realize the backlight device in direct-view display devices. However,this method also requires faster liquid crystal mode and it suffers halfof light energy lose.

U.S. Pat. No. 4,870,396 issued to Shields et al. on Sep. 26, 1989discloses a liquid crystal display driven by dual switching devices inone sub-pixel. FIG. 7 a shows the basic concept of LCD driving based ondual TFTs 710 in one sub-pixel. Each of these two TFTs has its ownfunction: one functions as a memory part to store the image data and theother as an imaging part to control the director orientation of theliquid crystal layer 720 by using the data stored in the memorycapacitor 708. In the figure, the data line 703 of the first TFT 701 isconnected to the data driver 240, as shown in FIG. 7B. The gate line 704of the first TFT 701 is connected to the scan driver 250. The drain 706of the first TFT 701 is connected to the source of the second TFT 702which is also connected to the first storage capacitor 707.

When the scan driver scans from the first row to the last row, imagedata are transferred to the first storage capacitor 707 through thefirst TFT 701. The stored data in the first capacitor 707 do nottransferred to the liquid crystal layer 720 immediately because thesecond TFT 702 is not activated yet during the scanning time. Therefore,the combination of the first capacitor 707 and the first TFT 701functions as a memory buffer. After scanning all rows, that is, afterfinishing writing one frame image data into the frame buffer, all secondTFTs 702 are activated simultaneously by triggering the gate lines 705.Consequently, the stored image data in the first capacitor 707 aretransferred to the second capacitor 708 to control the liquid crystallayer 720. FIG. 7 b shows the electrodes connection between sub-pixelsand drivers. Because each sub-pixel has two gate input lines G and VS,there are two lines in each sub-pixel which are connected to the scandriver.

The timing chart of the color sequential LCD driving based on the dualTFT method is shown in FIG. 8. During one sequence of the scanning therows of pixels along the timing lines 411, 412, and 413, the image dataof red, green, and blue sub-frame are transferred to the frame buffermemory. After the scanning process, data in the frame buffer aretransferred to the second capacitor in the sub-pixels at time points of801, 802, and 803, as shown in FIG. 8. Color of the backlight is changedsynchronously with the time of triggering the second TFTs. During onesub-frame period, the next sub-frame's image data are transferred to theframe buffer memory. The advantage of this method is it doesn't needdark sub-frames. Therefore, it doesn't lose energy of light.

SUMMARY OF THE INVENTION

The first objective of this invention is to provide apparatus, methods,system and devices for a transflective LCD with a pixel structureincluding at least three reflective sub-pixels and one transmissivesub-pixel.

The second objective of this invention is to provide apparatus, methods,system and devices for improved color reproduction capacity of thetransflective LCD for both transmissive and reflective images by usingcolor filters for the reflective sub-pixels to optimize the color filterproperty for the reflective images.

A third objective of the present invention is to provide apparatus,methods, system and devices for maximizing the color purity of thetransmissive image using a backlight which can switch the illuminationcolors sequentially.

The fourth objective of the present invention is to provide apparatus,methods, system and devices that use the same electro-optic responses inboth reflective and transflective modes in the transflective LCD withoutincreasing the complexity of fabrication processes.

A fifth objective of the present invention is to provide apparatus,methods, system and devices for driving the reflective sub-pixels andthe transmissive sub-pixel with independent TFTs so that theirelectro-optic curves overlap by using a double TFT driving concept.

A sixth objective of this invention is to provide apparatus, methods,system and devices for reducing the manufacturing cost of transflectiveLCD by eliminating complicated fabrication processes such as double cellgap, double domain alignment, and patterned retardation film.

A seventh objective of the present invention is to provide apparatus,methods, system and devices for reducing the manufacturing cost oftransflective LCD by eliminating the use of the dual thickness colorfilter for the optimization of the color purity for both transmissiveand reflective mode images to simplify the fabrication process andincrease the manufacturing yield.

An eighth objective of the present invention is to provide apparatus,methods, system and devices for producing a brighter image in comparisonto the image of prior art transflective LCDs.

In a first embodiment of the present invention, the transflective liquidcrystal display includes a top and a bottom substrate having a liquidcrystal layer sandwiched therebetween and plural pixels, each includingat least three reflective sub-pixels for displaying a reflective image,wherein each one of the at least three reflective sub-pixels having areflective layer on an inner surface of the bottom substrate to reflectan incident light back to a viewer, and a transmissive sub-pixel fordisplaying a transmissive image. At least one electronic circuit is usedfor driving the at least three reflective sub-pixels and thetransmissive sub-pixel of each one of the plural pixels and a backlightbelow the transmissive sub-pixels for producing a transmissive image anda timing control unit connected with the at least one electronic circuitconverts and distributes an incoming video data to the plural pixels andcontrolling the backlight to synchronize the reflective and transmissivedisplay images.

Each one of the plural pixels further includes at least three differentcolor filter layers located on one of the top and the bottom substrateof the at least three reflective sub-pixels, respectively, fordisplaying a reflective color image and at least three different colorlight sources below the transmissive sub-pixel are used to sequentiallytransmit a color transmissive image for each of the at least threedifferent colors. The at least one electronic circuit includes pluralfirst and second scan electrodes, and plural first and second dataelectrodes, wherein one of the plural first scan electrodes and one ofthe plural first data electrode connect each one of the at least threereflective sub-pixels to the at least one electronic circuit and one ofthe plural second scan electrodes and one of the plural second dataelectrodes connect each one of the transmissive sub-pixel to the atleast one electronic circuit.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a pixel of a prior art transflective liquid crystaldisplay.

FIG. 2 a is a schematic of the pixel electronic circuit having a singleswitch device.

FIG. 2 b is a schematic showing the electrode connection between thepixel electronics in FIG. 2 a and the driver electronic circuits.

FIG. 3 is a timing diagram of the prior art LCD operation.

FIG. 4 is a timing diagram of the color sequential LCD under the idealbacklight operation.

FIG. 5 is a timing diagram showing the color sequential LCD under thepulse type blinking backlight operation.

FIG. 6 is a timing diagram showing the color sequential LCD under theblinking type backlight operation using a dark sub-frame between twoprimary color sub-frames.

FIG. 7 a is a schematic showing the pixel electronics having dual switchdevices in each sub-pixel.

FIG. 7 b is a schematic showing the electrode connection between thepixel electronics shown in FIG. 7 a and the driver electronic circuits.

FIG. 8 is a timing diagram of the color sequential LCD with dualswitches in each sub-pixel under the blinking type backlight operation.

FIG. 9 shows the schematic pixel layout and structure according presentinvention showing the plural sub-pixels.

FIG. 10 a shows an example of the location of the pixel electronics inthe pixel structure of FIG. 9 according to the present invention.

FIG. 10 b shows an alternative location of the pixel electronics in thepixel structure shown in FIG. 9 according to the present invention.

FIG. 11 is a schematic diagram showing yet another alternative electrodeconnection between the pixel electronics and the driver electroniccircuits.

FIG. 12 is a timing diagram showing the operation of the reflectivesub-pixels and the transmissive sub-pixel of the transflective LCD shownin FIG. 11.

FIG. 13 is a timing diagram showing another example of the operation ofthe reflective sub-pixels and the transmissive sub-pixel of thetransflective LCD shown in FIG. 11.

FIG. 14 is a schematic diagram showing an alternative electrodeconnection between the pixel electronics and the driver electroniccircuits.

FIG. 15 is a timing diagram showing the operation of the reflectivesub-pixels and the transmissive sub-pixel of the transflective LCD shownin FIG. 14.

FIG. 16 is a timing diagram showing another example of the operation ofthe reflective sub-pixels and the transmissive sub-pixel of thetransflective LCD shown in FIG. 14

FIG. 17 is a schematic diagram showing an example of the electrodeconnection between the pixel electronics and the driver electroniccircuits.

FIG. 18 is a timing diagram showing an example of the operation of thereflective sub-pixels and the transmissive sub-pixel of thetransflective LCD shown in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before explaining the disclosed embodiments of the present invention indetail it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangements shown sincethe invention is capable of other embodiments. Also, the terminologyused herein is for the purpose of description and not of limitation.

The following is a list of the reference numbers used in the drawingsand the specification to identify components: 100 prior art pixelstructure 101 red sub-pixel 102 green sub-pixel 103 blue sub-pixel 111red transmission region 112 green transmission region 113 bluetransmission region 201 source terminal 202 gate terminal 203 drainterminal 210 pixel electronic circuit 211 thin film transistor 212capacitor 220 liquid crystal layer 230 vertical sync signal 240 datadriver 250 scan gate driver 311 first timing line 312 second timing line313 third timing line 314 fourth timing line 320 image data 401 red area402 green area 403 blue area 411 red timing line 412 green timing line413 blue timing line 520 image data 611 next scanning line 613 timingline 701 first thin film transistor 702 second thin film transistor 703data line 704 first gate line 705 second gate line 706 TFT drain 707first capacitor 708 memory capacitor 710 pixel electronic circuit 720liquid crystal layer 801 time one 802 time two 803 time three 901 firstreflective sub-pixel 902 second reflective sub-pixel 903 thirdreflective sub-pixel 904 transmissive sub-pixel 910 transflective pixel1011 first reflective pixel electronics 1012 second reflective pixelelectronics 1013 third reflective pixel electronics 1022 transmissivepixel electronic circuit 1101 pixel 1102 reflective sub-pixels 1103transmissive sub-pixel 1110 pixel electronic circuit 1120 timing controlunit 1130 backlight 1140 reflective data driver 1141 transmissive imagedata drivers 1150 reflective scan driver 1151 transmissive scan drivers1210 reflective timing graph 1211 timing line 1212 timing line 1220transmissive timing graph 1221 color sub-frame 1222 color sub-frame 1223color sub-frame 1231 color sub-frame timing 1232 color sub-frame timing1233 color sub-frame timing 1241 dark sub-frame timing 1242 darksub-frame timing 1243 dark sub-frame timing 1310 reflective graph 1311reflective scan time 1312 reflective scan time 1320 transmissive graph1321 color sub-frame 1322 color sub-frame 1323 color sub-frame 1331transmissive scan time 1332 transmissive scan time 1333 transmissivescan time 1401 pixel 1402 reflective sub-pixels 1403 transmissivesub-pixel 1410 reflective pixel electronic circuit 1411 transmissivepixel electronic circuit 1420 timing control unit 1430 backlight 1440reflective data driver 1441 transmissive image data driver 1450reflective scan driver 1451 transmissive scan driver 1510 reflectivetiming graph 1511 reflective frame scanning 1520 transmissive timinggraph 1531 first transmissive sub-frame scanning 1604 time 1610reflective timing diagram 1620 transmissive image timing 1621 firstcolor sub-frame 1622 second color sub-frame 1623 third color sub-frame1624 dark sub-frame 1633 scanning 1701 pixel 1702 reflective sub-pixels1703 transmissive sub-pixel 1710 pixel electronic circuit 1720 timingcontrol unit 1730 backlight 1740 first data driver 1741 second datadriver 1750 first scan driver 1751 second scan driver 1801 time 1804time 1810 reflective timing graph 1811 first reflective frame scan 1812reflective mode scan 1820 transmissive timing graph 1831 firsttransmissive sub-frame scan 1834 transmissive mode scan 1842 time point

The apparatus, methods, system and devices of the present inventionprovide a transflective liquid crystal display having a pixel structureincluding at least three sub-pixels for the reflective part and onesub-pixel for the transmissive part. The sub-pixel for the reflectivepart has a reflective mirror and a color filter for showing a colorimage by reflecting an ambient light. To produce a color image intransmissive part of the LC display, a sequentially switched color lightfrom a backlit unit device is used and the transmissive color image isdrawn using a series of primary color images. The reflective sub-pixelsand the transmissive sub-pixel are independently switched by switchingdevices such as thin film transistors. As a result of using independentswitch devices for the transmissive and reflective parts, theelectro-optical performance curves of both transmissive display mode andreflective display mode can overlap with each other very well. Theswitching devices and related peripheral electronics for both reflectiveand transmissive sub-pixels are located under the reflectors of thereflective sub-pixels on the bottom substrate. This electronic structureusing a single transmissive sub-pixel configuration improves theaperture sizes of both reflective and transmissive sub-pixels compare toprior art. As a result, brighter image for both reflective andtransmissive modes is produced.

FIG. 9 shows a schematic structure and pixel layout of a transflectiveliquid crystal display of the present invention. As shown, each pixel910 includes three reflective sub-pixels 901, 902, and 903 fordisplaying a reflective image and one transmissive sub-pixel 904 fordisplaying a transmissive image. Each reflective sub-pixel has areflective mirror located on the inner surface of the bottom substrateto reflect the incident light back to the viewer. To obtain a colorimage, the reflective mode uses at least three primary color sub-pixelswhich have color filter layers located either on the bottom substrate oron the top substrate of the LCD. In the present invention, the threesub-pixels 901, 902, and 903 correspond to three primary colorsub-pixels which are used to display a color reflective image.

To display a transmissive image, one transmissive sub-pixel 904 is used.This transmissive sub-pixel 904 transmits the light from a backlightsource which is behind the LCD panel. To display a full colortransmissive image in the transmissive sub-pixel 904, at least threedifferent primary color lights transmit the transmissive sub-pixel 904sequentially during one frame period, with one primary color light ineach sub-frame of the frame period. When the frame frequency is highenough, typically greater than approximately 30 frame/second, the viewersee a full color image. The method for displaying the transmissive colorimage is referred to as a color sequential imaging method.

In an embodiment of the present invention, each of those sub-pixels 901,902, 903, and 904 is driven by an independent electronic switchcomprising at least one thin film transistor and at least one capacitor.FIG. 10 a shows the location of sub-pixel electronic circuits in thepresent invention according to the first embodiment. As shown, the firstreflective sub-pixel 901 has an electronic circuit 1011, the secondreflective sub-pixel 902 is driven by with electronic circuit 1012, thethird reflective sub-pixel 903 is driven by electronic circuit 1013, andthe transmissive sub-pixel 904 is driven by electronic circuit 1014 aswell.

Each sub-pixel's electronic circuit is within the region of thecorresponding sub-pixel. In the three reflective sub-pixels, eachsub-pixel has an opaque reflective mirror and the electronic circuitsare located under the reflective mirror. As a result, the electroniccircuits themselves do not affect the aperture ratio of the reflectivesub-pixel, yielding a large aperture size and high light utilizationefficiency. On the other hand, in the transmissive sub-pixel, theelectronic circuits occupy a portion of the sub-pixel area which blockspart of the backlight. As a result, the aperture size is reduced and thebrightness of image decreases.

FIG. 10B shows the second embodiment of the location of sub-pixelelectronic circuits in the present invention. To increase the apertureratio of the transmissive sub-pixel 904, the sub-pixel electroniccircuits 1022 is also located under the reflectors of the reflectivesub-pixels 901, 902, and 903. In this embodiment, the aperture ratio ofall sub-pixels is maximized. Unlike the prior art transflective LCD'spixel structure shown in FIG. 1, the pixel structure of the presentinvention shown in FIG. 10 b increases the size of all sub-pixels.

In the prior art transflective LCD, each pixel is divided into threedifferent primary color sub-pixels. And the size of each sub-pixelequals to each other. Each sub-pixel has a discontinuous reflector filmso that some part of the sub-pixel is transparent and the other part ofthe sub-pixel is opaque. The transparent part allows the backlight passthrough it while the opaque part serves as the reflector to reflect theincident ambient light back to the viewers' eyes. As an example, eachone of the three sub-pixels has an area ratio of the transmissive partto the reflective part of approximately 6:4. Therefore, area size of thetransmissive part of each sub-pixel occupies approximately 20 percent ofone entire pixel size, and the area size of the reflective part of eachsub-pixel occupies about 13 percent of one entire pixel size.

In the liquid crystal display of the present invention, one pixel isdivided into four equal sized sub-pixels, three reflective sub-pixelsand one transmissive sub-pixel. The area size of each sub-pixel isapproximately 25 percent of one entire pixel size. In the transflectiveLCD of the present invention, the area size of the transmissivesub-pixel increases 25 percent while the area size of the reflectivesub-pixels increases 92 percent. As a result, the display has brighterimage or can have lower power consumption in comparison with theconventional transflective LCDs.

FIG. 11 shows the third embodiment of the present invention based on thepixel structure shown in FIG. 9. In the figure, one pixel 1101 has threereflective sub-pixels 1102 and one transmissive sub-pixel 1103. Thereflective sub-pixels 1102 are driven by the scan driver 1150 and thedata driver 1140, while the transmissive sub-pixels 1103 is driven bythe scan drivers 1151 and the data drivers 1141. In an embodiment of thepresent invention, both reflective sub-pixels 1102 and transmissivesub-pixels 1103 are driven by a single-switch based electronic circuit1110. The video data is converted by a timing control unit 1120 and isdistributed to the data drivers 1140 and 1141 and scan drivers 1150 and1151 for the reflective and transmissive sub-pixels, respectively. Thetiming control unit 1120 also controls the backlight 1130 to synchronizethe display of the reflective and transmissive color images.

FIG. 12 shows an example of the operation timing diagram of thetransflective LCD shown in FIG. 11. The top graph 1210 is the timingdiagram for displaying the reflective image and the bottom graph 1220shows the timing diagram for displaying the transmissive image. Alongtiming lines 1211 and 1212, reflective sub-pixels are scanned by thescan driver 1150 and the first and the second frame images are drawn,respectively. During one frame period, the transmissive sub-pixels 904are scanned six times along the timing lines 1231, 1241, 1232, 1242,1233, and 1243, during which the three timing lines 1231, 1232, and 1233are for the three primary color sub-frames 1221, 1222, and 1223 and thethree timing lines 1241, 1242, and 1243 are for the three darksub-frames. During the three timing lines 1231, 1232, and 1233, thetransmissive data driver transfers the color image data to thetransmissive sub-pixels, while during the three timing lines 1241, 1242,and 1243, the transmissive data driver transfers the dark image data tothe transmissive sub-pixels. In other words, the color sub-frame and thedark sub-frame are interleaved within the six sub-frames period. Tosynchronize the reflective image with transmissive image, the firstsub-frame scanning 1231 of the transmissive mode coincides with theframe scanning 1221 of the reflective mode. To produce the color image,the first primary color of the backlight is activated between the timepoint when the first row of the transmissive sub-pixels are scanned atthe first sub-frame scanning and the time point when the first row ofthe transmissive sub-pixels are scanned at the third sub-frame scanning.As the same manner, the second primary color of the backlight isactivated between the time point when the first row of the transmissivesub-pixels are scanned at the third sub-frame scanning and the timepoint when the first row of the transmissive sub-pixels are scanned atthe fifth sub-frame scanning, and the third primary color of thebacklight is activated between the time point when the first row of thetransmissive sub-pixels are scanned at the fifth sub-frame scanning andthe time point when the first row of the transmissive sub-pixels arescanned at the first sub-frame scanning for the next frame. Therefore,the backlight is looked to switch its color on entire lighting area at amoment. To produce the dark image during the second, fourth, and sixthsub-frames of the transmissive sub-pixels, dark image data aretransferred from the data driver to the entire transmissive sub-pixelsfollowing the second, fourth, and sixth sub-frame scanning.

FIG. 13 shows the second example of the operation timing diagram of thetransflective LCD in the third embodiment of the present invention asshown in FIG. 11. The top graph 1310 is the timing diagram fordisplaying the reflective image and the bottom graph 1320 is fordisplaying the transmissive image. During the time corresponding totiming lines 1311 and 1312, reflective sub-pixels are scanned by thescan driver 1150 and the first and the second frame images are drawn,respectively. During one frame period, the transmissive sub-pixels 904are scanned three times along the timing lines 1331, 1332, and 1333.During each scan, after the last row is selected by the scan driver1150, the primary color backlight is activated between the time pointwhen the last row of the transmissive sub-pixels are scanned for thefirst sub-frame scanning and the time point when the first row of thetransmissive sub-pixels are scanned for the second sub-frame. As a samemanner, the second primary color backlight is activated between the timepoint when the last row of the transmissive sub-pixels are scanned forthe second sub-frame scanning and the time point when the first row ofthe transmissive sub-pixels are scanned for the third sub-framescanning, and the third primary color backlight is activated between thetime point when the last row of the transmissive sub-pixels are scannedfor the third sub-frame scanning and the time point when the first rowof the transmissive sub-pixels are scanned for the first sub-framescanning of the next frame imaging. As a result, the corresponding colorsub-frame images are shown during the time period of 1321, 1322, and1323 in the transmissive display mode. In this case, the image of wholearea is drawn at a moment although the transmissive image data aretransferred to the transmissive sub-pixels row by row.

FIG. 14 shows an alternative configuration of the transflective LCD inthe present invention. As previously described, each pixel 1401comprises three reflective sub-pixels 1402 and one transmissivesub-pixel 1403. However, the reflective sub-pixels 1402 are driven by asingle electronic circuit 1410, while the transmissive sub-pixel 1403 isdriven by dual-switch based electronic circuits 1411 as explained in thedescription of the configuration shown in FIG. 7A. The reflectivesub-pixels 1402 are connected with the scan driver 1450 and the datadriver 1440. The transmissive sub-pixels 1403 are connected with thescan driver 1451 and the data driver 1441. The video data are convertedby a timing control unit 1420 and is further distributed to all datadrivers 1440 and 1441 and scan drivers 1450 and 1451. Timing controlunit 1420 also synchronizes the backlight 1430 operation with thetransmissive sub-pixel 1403 operation. In addition, it synchronizes thereflective image displayed by the reflective sub-pixels 1402 with thetransmissive image displayed by the transmissive sub-pixels 1403.

FIG. 15 shows the first example of the operation timing diagram of thetransflective LCD in the fourth embodiment of the present invention asshown in FIG. 14. The top graph 1510 is the timing diagram fordisplaying the reflective image and the bottom graph 1520 shows thetiming diagram for displaying the transmissive image. One frame scanning1511 of the reflective mode coincides with the first sub-frame scanning1531 of the transmissive mode. Reflective mode holds the image data forthree sub-frame periods of the transmissive mode. The transmissive modedraws the whole area of the image at one time by using the frame buffermethod previously described in regard to the configuration shown in FIG.8. To synchronize the backlight operation with sub-frames oftransmissive mode, each primary color is activated during the timeperiod between the time point when the first row of the transmissivesub-pixels are scanned for one sub-frame and the time point when thefirst row of the transmissive sub-pixels are scanned for the followingsub-frame. Because of the difference of imaging method betweenreflective and transmissive mode, image holding times of thetransmissive mode in the first and the third sub-frames are notsynchronized with that of the reflective mode.

To solve the above problem, FIG. 16 shows another example of theoperation timing diagram of the transflective LCD shown in FIG. 14. Thetop graph 1610 is the timing diagram for displaying the reflective imageand the bottom graph 1620 is for displaying the transmissive image. Inthe transmissive display mode 1620, one dark sub-frame 1624 isintroduced after the third sub-frame 1623. The data of the darksub-frame 1624 are transferred to the frame buffer memory together withthe scanning 1633, and further are sent to the imaging part, liquidcrystal layer, at the time 1604. In addition, the backlight isturned-off during the dark sub-frame period. Unlike the timing diagramshown in FIG. 15, in this example, the first and last sub-frames in thetransmissive mode match with the beginning and end of one frame in thereflective mode.

FIG. 17 is a schematic diagram showing another configuration of thetransflective LCD according to the present invention. Like the previousexamples, each pixel 1701 comprises three reflective sub-pixels 1702 andone transmissive sub-pixel 1703, however, both reflective sub-pixels1702 and transmissive sub-pixels 1703 are driven by dual-switch basedpixel electronic circuits 1710 as previously described in regard to theconfiguration shown in FIG. 7A. The reflective sub-pixels 1702 areconnected with the scan driver 1750 and the data driver 1740 while thetransmissive sub-pixels 1703 are connected with the scan driver 1751 andthe data driver 1741. The video data are converted by a timing controlunit 1720 and is further distributed to all data drivers 1740 and 1741and scan drivers 1750 and 1751. Timing control unit 1720 alsosynchronizes the backlight 1730 operation with the transmissivesub-pixel 1703 operation. In addition, it synchronizes the reflectiveimage displayed by the reflective sub-pixels 1702 with the transmissiveimage displayed by the transmissive sub-pixels 1703.

FIG. 18 shows the operation timing diagram of the transflective LCDconfiguration shown in FIG. 17. The top graph 1810 is the timing diagramfor displaying the reflective image and the bottom graph 1820 is fordisplaying the transmissive image. By using dual-switch based drivingmethod for both transmissive and reflective modes, it is easy to overlapthe transmissive image with the reflective images. The first framescanning 1811 of the reflective mode coincides with the first sub-framescanning 1831 of the first frame of transmissive mode. After finishingthe first frame scanning 1811 of the reflective mode and the firstsub-frame scanning 1831 of the first frame of transmissive mode, data inthe frame buffer of transmissive and reflective sub-pixels aretransferred to the second capacitor in the sub-pixels at the same timepoint 1801 and 1841. The reflective image is hold for three sub-framestime of the transmissive mode and the transmissive image of each primarycolor is hold for one sub-frame time of the transmissive mode.

During the third sub-frame period of the transmissive image, image datafor the second frame image of the reflective mode and data for the firstsub-frame image of the second fame of the transmissive mode aretransferred to the frame buffer memory of both reflective andtransmissive sub-pixels along the timing line of reflective modescanning 1812 and the timing line of transmissive mode scanning 1834.After finishing scanning 1812, data for reflective image in the framebuffer memory are transferred to the second capacitor in the reflectivesub-pixels by triggering the second TFT's gate at the time point 1842.As the same manner, data for transmissive image in the frame buffermemory are transferred to the second capacitor in the transmissivesub-pixels at the time point 1804. Timing control unit 1720 synchronizesthe time point 1842 with the time point 1804. Due to this timingsynchronization, the image frame of the transmissive mode can matchperfectly with the image frame of the reflective mode without darksub-frames used in the fourth embodiment as shown in FIG. 16. Tosynchronize the backlight operation with sub-frames of transmissivemode, each primary color is activated as the same manner described inFIG. 15.

While the invention has been described, disclosed, illustrated and shownin various terms of certain embodiments or modifications which it haspresumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

1. A transflective liquid crystal display comprising: a top and a bottomsubstrate having a liquid crystal layer sandwiched between the top andthe bottom substrate; plural pixels, each one of the plural pixelscomprising: at least three reflective sub-pixels for displaying areflective image, wherein each one of the at least three reflectivesub-pixels having a reflective layer on an inner surface of the bottomsubstrate to reflect an incident light back to a viewer; and atransmissive sub-pixel for displaying a transmissive image; at least oneelectronic circuit for driving the at least three reflective sub-pixelsand the transmissive sub-pixel of each one of the plural pixels; abacklight below the transmissive sub-pixels; and a timing control unitconnected with the at least one electronic circuit for converting anddistributing an incoming video data to the plural pixels and controllingthe backlight to synchronize the reflective and transmissive displayimages.
 2. The transflective liquid crystal display of claim 1, whereineach one of the plural pixels further comprises: at least threedifferent color filter layers located on one of the top and the bottomsubstrate of the at least three reflective sub-pixels, respectively,wherein the at least three color filter layers display a reflectivecolor image using incoming light from ambient; and at least threedifferent color light sources below the transmissive sub-pixel tosequentially transmit a color transmissive image for each of the atleast three different colors during one time frame.
 3. The transflectiveliquid crystal display of claim 1, wherein the at least one electroniccircuit comprises: plural first and second scan electrodes; and pluralfirst and second data electrodes, wherein one of the plural first scanelectrodes and one of the plural first data electrode connect each oneof the at least three reflective sub-pixels to the at least oneelectronic circuit and one of the plural second scan electrodes and oneof the plural second data electrodes connect each one of thetransmissive sub-pixel to the at least one electronic circuit.
 4. Thetransflective liquid crystal display of claim 3, wherein the at leastone electronic circuit comprises: at least four pixel electroniccircuits connected with the plural first and second scan electrodes andthe plural first and second data electrodes for driving the at leastthree reflective sub-pixel and the transmissive sub-pixel, respectively,for each of the plural pixels, wherein the at least four pixelelectronic circuits are each located in a region of a corresponding oneof the at least three reflective sub-pixel and the transmissivesub-pixel.
 5. The transflective liquid crystal display of claim 4,wherein at least three of the at least four pixel electronic circuitsare each located below the reflective layer of a corresponding one ofthe at least three reflective sub-pixels to increase an aperture ratioof the at least three reflective sub-pixel to provide brighterreflective image for the reflective modes.
 6. The transflective liquidcrystal display of claim 4, wherein the one of the at least four pixelelectronic circuits drives the transmissive sub-pixel and is eachlocated below the reflective layer of the at least three reflectivesub-pixels to increase an aperture ratio of the transmissive sub-pixelto provide a brighter transmissive image for the transmissive mode. 7.The transflective liquid crystal display of claim 3, wherein the atleast one electronic circuit further comprises: a reflective pixelelectronic circuit connected with the plural first scan and first dataelectrodes for driving each one of the at least three reflectivesub-pixels; and a dual-switch based transmissive pixel electroniccircuit connected with the plural second scan and second data electrodesfor driving the transmissive sub-pixel.
 8. The transflective liquidcrystal display of claim 7, wherein the dual-switch based transmissivepixel electronic circuit comprises: a first and a second thin filmtransistor; and a first and second charge holding device connected witha first and second thin film transistor to connect the plural secondscan and second data electrodes to drive the transmissive sub-pixels ofthe plural pixels, wherein the first thin film transistor and firstcapacitor functions as a frame memory part and the second thin firmtransistor and second capacitor functions as a liquid crystal driver. 9.The transflective liquid crystal display of claim 3, wherein the atleast one electronic circuit further comprises: a reflective scan driverand a reflective image data driver connected with the at least threereflective sub-pixels; and a transmissive scan driver and a transmissiveimage data driver connected with the transmissive sub-pixel, wherein thetiming control unit converts and distributes a video data to thereflective data and scan drivers and the transmissive image data andscan drivers.
 10. The transflective liquid crystal display of claim 3,wherein the at least one electronic circuit further comprises: adual-switch based reflective pixel electronic circuit connected with theplural first scan and first data electrodes for driving each one of theat least three reflective sub-pixels; and a dual-switch basedtransmissive pixel electronic circuit connected with the plural secondscan and second data electrodes for driving the transmissive sub-pixel.11. The transflective liquid crystal display of claim 1, wherein thetiming control unit further comprises: a reflective timing signal forscanning the reflective sub-pixels row-by-row once during each one ofplural frame periods; and a transmissive timing signal for scanning thetransmissive sub-pixels row-by-row for six sub-frames during each one ofthe plural frame periods, wherein a color sub-frame and a dark sub-frameare interleaved within the six sub-frames.
 12. The transflective liquidcrystal display of claim 11, wherein the reflective timing signal andthe transmissive timing signal further comprises: a synchronization ofthe scanning of the reflective and transmissive sub-pixels during thefirst sub-frame in each frame period.
 13. The transflective liquidcrystal display of claim 12, further comprising: a transmissive colorsignal having six sub-frame periods per time period, wherein a first oneof the at least three different color light is activated between a firsttime point when a first row of transmissive sub-pixels are scanned at afirst sub-frame scanning and a second time point when the first row ofthe transmissive sub-pixels are scanned at a second sub-frame scanning;a second one of the at least three different color light source isactivated between the second time point when the first row of thetransmissive sub-pixels are scanned during the second sub-frame scanningand a third time point when the first row of the transmissive sub-pixelsare scanned during a fifth sub-frame scanning; and a third one of the atleast three different color light sources is activated between the thirdtime point when the first row of the transmissive sub-pixels are scannedat a fifth sub-frame scanning and the first time point when the firstrow of the transmissive sub-pixels are scanned at next first sub-framescanning of the next frame imaging.
 14. The transflective liquid crystaldisplay of claim 1, wherein the timing control unit further comprises: areflective timing signal for scanning the reflective sub-pixelsrow-by-row once during each one of plural frame periods; and atransmissive timing signal for scanning the transmissive sub-pixelsrow-by-row for six sub-frames during each one of the plural frameperiods
 15. The transflective liquid crystal display of claim 14,wherein the transmissive timing signal further comprises: asynchronization of the reflective timing signal with the transmissivetiming signal for synchronizing the scanning of the transmissivesub-pixels in a first one of the three sub-frames with the scanning ofthe first, second and third reflective sub-pixels during the frame timeperiod.
 16. The display of claim 15, wherein the scanning period of eachsub-frame of the transmissive sub-pixels is less than approximately ⅓ ofone frame period.
 17. The transflective liquid crystal display of claim14, further comprising: a scanning period having a time interval from abeginning time point when the first row of transmissive sub-pixels arescanned through an end time point when the last row transmissivesub-pixels are scanned during one sub-frame period.
 18. Thetransflective liquid crystal display of claim 14, further comprising: afirst one of the at least three different color light sources isactivated between a first time point when a last row of the transmissivesub-pixels are scanned for a first sub-frame scanning and a second timepoint when the first row of the transmissive sub-pixels are scanned fora second sub-frame scanning; a second one of the at least threedifferent color light sources is activated between the second time pointwhen the last row of the transmissive sub-pixels are scanned for thesecond sub-frame scanning and a third time point when the first row ofthe transmissive sub-pixels are scanned for the third sub-framescanning; and a third one of the at least three different color lightsources is activated between the third time point when the last row ofthe transmissive sub-pixels are scanned for the third sub-frame scanningand the first time point when the first row of the transmissivesub-pixels are scanned for the first sub-frame scanning of a next frameimaging.
 19. The transflective liquid crystal display of claim 1,wherein the timing control unit further comprises: a reflective timingsignal for scanning the reflective sub-pixels row-by-row once duringeach one of plural frame periods; and a transmissive timing signal forscanning the transmissive sub-pixels row-by-row for six sub-framesduring each one of the plural frame periods.
 20. The transflectiveliquid crystal display of claim 19, wherein the transmissive timingsignal further comprises: a synchronization of the reflective timingsignal with the transmissive timing signal for synchronizing thescanning of the transmissive sub-pixels in a first one of the threesub-frames with the scanning of the first, second and third reflectivesub-pixels during the frame time period.
 21. The transflective liquidcrystal display of claim 20, further comprising: a transmissive imagedata are transferred to an image buffer memory in the transmissive pixelelectronics during the transmissive sub-frame scanning.
 22. Thetransflective liquid crystal display of claim 21, wherein thetransmissive image data in the image buffer are transferred to thesecond charge holding devices to apply voltage to liquid crystal layerin the transmissive pixel electronics at time point after the last rowof the transmissive sub-pixels are scanned for each of sub-framescanning to draw the image.
 13. The transflective liquid crystal displayof claim 20, wherein a first one of the at least three different colorlight is activated between the time point when the last row of thetransmissive sub-pixels are scanned for the first sub-frame scanning andthe time point when the last row of the transmissive sub-pixels arescanned for the second sub-frame scanning; whererin a second one of theat least three different color light is activated between the time pointwhen the last row of the transmissive sub-pixels are scanned for thesecond sub-frame scanning and the time point when the last row of thetransmissive sub-pixels are scanned for the third sub-frame scanning;and wherein a third one of the at least three different color light isactivated between the time point when the last row of the transmissivesub-pixels are scanned for the third sub-frame scanning and the timepoint when the last row of the transmissive sub-pixels are scanned forthe first sub-frame scanning of the next frame imaging.
 23. Thetransflective liquid crystal display of claim 1, wherein the timingcontrol unit further comprises: a reflective timing signal for scanningthe reflective sub-pixels row-by-row once during each one of pluralframe periods; and a transmissive timing signal for scanning thetransmissive sub-pixels row-by-row for six sub-frames during each one ofthe plural frame periods.
 24. The transflective liquid crystal displayof claim 23, wherein the transmissive timing signal further comprises: asynchronization of the reflective timing signal with the transmissivetiming signal for synchronizing the scanning of the transmissivesub-pixels in a first one of the three sub-frames with the scanning ofthe first, second and third reflective sub-pixels during the frame timeperiod.
 25. The transflective liquid crystal display of claim 24,further comprising: a transmissive image data are transferred to animage buffer memory in the transmissive pixel electronics during thetransmissive sub-frame scanning.
 26. The transflective liquid crystaldisplay of claim 25, wherein the transmissive image data in the imagebuffer memory are transferred to the second charge holding devices toapply voltage to liquid crystal layer in the transmissive pixelelectronics at time point after the last row of the transmissivesub-pixels are scanned for each of sub-frame scanning to draw thetransmissive image.
 27. The transflective liquid crystal display ofclaim 23, wherein the transmissive image data transferred during afourth sub-frame scanning are a dark image data.
 28. The transflectiveliquid crystal display of claim 23, further comprising a first one ofthe at least three different color light is activated between the timepoint when the last row of the transmissive sub-pixels are scanned forthe first sub-frame scanning and the time point when the last row of thetransmissive sub-pixels are scanned for the second sub-frame scanning; asecond one of the at least three different color light is activatedbetween the time point when the last row of the transmissive sub-pixelsare scanned for the second sub-frame scanning and the time point whenthe last row of the transmissive sub-pixels are scanned for the thirdsub-frame scanning; and a third one of the at least three differentcolor light is activated between the time point when the last row of thetransmissive sub-pixels are scanned for the third sub-frame scanning andthe time point when the last row of the transmissive sub-pixels arescanned for the fourth sub-frame scanning.
 29. The transflective liquidcrystal display of claim 23, wherein a backlight is deactivated betweenthe time point when the last row of the transmissive sub-pixels arescanned for the fourth sub-frame scanning and the time point when thelast row of the transmissive sub-pixels are scanned for the firstsub-frame scanning of the next frame imaging.
 30. The transflectiveliquid crystal display of claim 1, wherein the timing control unitfurther comprises: a reflective timing signal for scanning thereflective sub-pixels row-by-row once during each one of plural frameperiods; and a transmissive timing signal for scanning the transmissivesub-pixels row-by-row for six sub-frames during each one of the pluralframe periods.
 31. The transflective liquid crystal display of claim 30,wherein the transmissive timing signal further comprises: asynchronization of the reflective timing signal with the transmissivetiming signal for synchronizing the scanning of the transmissivesub-pixels in a first one of the three sub-frames with the scanning ofthe first, second and third reflective sub-pixels during the frame timeperiod.
 32. The transflective liquid crystal display of claim 30,further comprising: a transmissive image data are transferred to animage buffer memory in the transmissive pixel electronics during thetransmissive sub-frame scanning and a reflective image data aretransferred to an image buffer memory in the reflective pixelelectronics during the reflective frame scanning.
 33. The display ofclaim 31, wherein the reflective image data in the frame buffer aretransferred to the second charge holding devices to apply voltage toliquid crystal layer in the reflective pixel electronics at time pointafter the last row of the reflective sub-pixels are scanned for eachframe scanning to draw the reflective image.
 34. The display of claim31, wherein the transmissive image data in the frame buffer aretransferred to the second charge holding devices to apply voltage toliquid crystal layer in the transmissive pixel electronics at time pointafter the last row of the transmissive sub-pixels are scanned for eachof sub-frame scanning to draw the image.
 35. The transflective liquidcrystal display of claim 30, further comprising: a first one of the atleast three different color light is activated between the time pointwhen the last row of the transmissive sub-pixels are scanned for thefirst sub-frame scanning and the time point when the last row of thetransmissive sub-pixels are scanned for the second sub-frame scanning; asecond one of the at least three different color light is activatedbetween the time point when the last row of the transmissive sub-pixelsare scanned for the second sub-frame scanning and the time point whenthe last row of the transmissive sub-pixels are scanned for the thirdsub-frame scanning; and a third one of the at least three differentcolor light is activated between the time point when the last row of thetransmissive sub-pixels are scanned for the third sub-frame scanning andthe time point when the last row of the transmissive sub-pixels arescanned for the first sub-frame scanning of the next frame imaging. 36.A transmissive liquid crystal display system comprising: a liquidcrystal layer sandwiched between a first and a second substrate; pluralpixels having at least three opaque reflective sub-pixels and atransparent transmissive sub-pixel for displaying a reflective image anda transmissive image, respectively, the at least three opaque reflectivesub-pixels having a reflective layer for reflecting a light back to aviewer; a backlight coupled with the transmissive sub-pixels fordisplaying the transmissive image; at least one electronic circuit fordriving the plural pixels, the driver having a reflective scan driver, areflective data driver, a transmissive scan driver and a transmissiveimage data driver; plural reflective scan electrodes and data electrodesto connect the at least three reflective sub-pixels of the plural pixelsto the reflective scan and data drivers, respectively; pluraltransmissive scan electrodes and data electrodes to connect thetransmissive sub-pixels of the plural pixels to the transmissive scanand data drivers, respectively; an operation timing control unitconnected with the at least one driver for controlling the operation ofthe reflective scan driver, reflective data driver, transmissive scandriver and transmissive image data driver to synchronize the reflectivesub-pixels and transmissive sub-pixels for displaying a reflective and atransmissive image, respectively.
 37. A method to produce atransflective liquid crystal display device, including the steps of:providing a liquid crystal display having a liquid crystal layersandwiched between a top and a bottom substrate; forming plural pixelsin the liquid crystal display; sub-dividing each one of the pluralpixels into at least three reflective sub-pixels and at least onetransmissive sub-pixels; scanning the at least three reflectivesub-pixels and at least one transmissive sub-pixel of the plural pixels;and synchronizing the scanning of the at least three reflectivesub-pixels for displaying a reflective image and the at least onetransmissive sub-pixels for displaying a transmissive image; andsynchronizing the scanning of the at least one transmissive sub-pixelsand the activating each of at least three primary color of backlight.